JPH054783B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a sealed lead acid battery.

Conventional Technology Sealed lead-acid batteries, which are now frequently used as power supplies for portable equipment such as portable VCRs, have been developed to improve volumetric efficiency and energy density, and to prevent leakage no matter what position they are used in. Therefore, the structure and composition are designed to reduce the amount of electrolyte as much as possible compared to general lead-acid batteries. For this reason, a manufacturing method is usually adopted in which a chemically formed electrode plate is used and a usable battery can be made by injecting a small amount of electrolyte.

Problems to be Solved by the Invention Therefore, it has been difficult to provide an inexpensive battery because the process and man-hours required to chemically form the electrode plates are time-consuming. In addition, when manufacturing a retainer type lead-acid battery using the in-container chemical conversion method, there is an advantage of reducing the cost of the chemical conversion process for both the positive and negative electrode plates, but the liquid level rises due to gas generation before and after charging is completed. Therefore, if a large amount of dilute sulfuric acid, which has a relatively low specific gravity and is commonly used in battery cell formation, is used in abundance, there is a problem in that the liquid tends to leak out of the battery.

On the other hand, if battery cell formation is performed when the electrolyte is low, the electrolyte will be significantly reduced due to the electrolysis of water just before charging is completed, resulting in poor battery performance, especially self-discharge characteristics and recovery after overdischarge. I get tired.
Therefore, battery cell formation is carried out by adjusting the amount and specific gravity of the electrolyte to keep the rise in the liquid level due to gas generation directly above the electrode plate group. During the formation of the battery case, the gas becomes bubbles and ruptures on the liquid surface, and the droplets from this case adhere to the back of the inner lid and the exhaust hole, and the water vapor condensed from the heat generated during the formation of the battery case grows as the formation progresses. However, as the exhaust hole is eventually blocked, the gas that has no escape route fills the battery and becomes pressurized, forcing water droplets (including electrolyte) that have blocked the exhaust hole out of the battery. There was a problem.

The present invention aims to prevent the above-mentioned conventional problem from overflowing during the formation of a battery case for a storage battery having a small exhaust hole.

Means for Solving the Problems The present invention provides that the lower part of the exhaust hole of the lid covering the case of a sealed lead-acid battery is made into a mortar shape with an edge on the outer periphery, and the left and right sides sandwich the exhaust hole. A descending wall parallel to the outside and a descending wall connecting this descending wall and the outer periphery of the mortar-shaped lower part of the exhaust hole are provided.

The surface tension generated at the bottom of the exhaust hole is used to prevent electrolyte from overflowing.

Action The countless small water droplets containing electrolyte that adhere to the entire inner lid including the exhaust hole due to the splashes and condensation of water vapor during the formation of the battery gradually grow larger over time, but this process is caused by the interaction with surrounding water droplets. The water droplets attract each other and are attracted to the one with the higher surface tension, growing into a larger droplet at an accelerated pace. Furthermore, if there is a protrusion or the like, the surface tension at the corner is large, so that the protrusions gather there. The present invention takes advantage of this effect by providing falling walls corresponding to these protrusions on both left and right sides of the outside of the exhaust hole, and by collecting and growing water droplets around the exhaust hole on these walls, the water droplets are collected inside the exhaust hole. The attached and grown water droplets are drawn to the wall and allowed to fall under their own weight before closing the exhaust hole. According to the present invention, it is possible to completely prevent overflow during battery cell formation, which has been a problem in the prior art.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a sealed lead-acid battery according to an embodiment of the present invention, and FIG. 2 is a back view of the inner lid. In the figure, 1 is a battery case, 2 is an inner lid that covers the battery case, 3 is an electrode plate, 4 is an electrolyte, 5 is a cap-shaped safety valve, 6
is an exhaust hole, which is provided in a mortar-like edge so as to open downward from the inside to the outside, and a downward wall 8 parallel to both sides of the exhaust hole, and a lower outer periphery of this downward wall and the mortar-shaped part 7. This is shown in FIG. 3 with a descending wall 9 connecting the two.

The space 10 created at the corner between the outer periphery of the mortar-shaped part 7 and the descending walls 8 and 9 has walls on three sides, so it becomes a space with the highest surface tension within the inner lid, and when forming the battery case, this space 10 is It is possible to concentrate the water droplets that are generated. The water droplets that are concentrated here and grow large have strong surface tension,
The water droplets gradually descend downward along the outer periphery of the mortar-shaped portion 7. On the other hand, as the water droplets generated inside the exhaust hole 6 grow,
It descends downward along the inner wall due to its own weight, and when it reaches the edge of the mortar-shaped part 7, it is attracted by the water droplets collected at the corner part. When the water droplets collected at the corners grow to the point where they can no longer withstand their own weight, they fall naturally. In this way, the water droplets generated in the exhaust hole are attracted to the water droplets in the corners before blocking the exhaust hole, so that overflow during battery cell formation can be completely prevented.

Effects of the Invention As described above, in the case of batteries using the structure according to the present invention and chemically formed inside the battery case, if this structure was not adopted, approximately 8% of the cells would have leaked liquid outside the battery. On the other hand, almost no leakage was observed. Furthermore, work efficiency in processes after the chemical conversion process inside the battery case is significantly improved, and there is no need to use parts such as splash-proof plates, which reduces material costs and man-hours, making it possible to provide cheaper batteries. Furthermore, since the electrolyte does not leak out of the battery, the quality of the product is stabilized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a sealed lead-acid battery according to an embodiment of the present invention, FIG. 2 is a back view of the inner lid, and FIG. 3 is a perspective view of the inner lid viewed from below. 1...Battery case, 2...Inner lid, 3...Pole plate, 4...
...Electrolyte, 5...Safety valve, 6...Exhaust hole, 7...
Suribachi-shaped part, 8, 9...downward wall, 10...corner space.

Claims (1)

[Claims] 1. A group of electrode plates consisting of a positive electrode made of lead dioxide as an active material, a negative electrode made of spongy lead as an active material, and a fine glass fiber separator interposed between the positive and negative electrodes is housed in a battery case, and the battery is evacuated. A sealed lead-acid battery covered with a lid having holes and having an electrolyte occluded in the electrode plate group, wherein the lower part of the exhaust hole is shaped like a mortar so that the outer peripheral edge is an edge, A sealed lead-acid battery characterized in that a descending wall parallel to the left and right outer sides sandwiching an exhaust hole, and a descending wall connecting the descending wall and the outer periphery of the mortar-shaped lower part of the exhaust hole are provided.